Preliminary results after first round of voting show left-leaning economist well placed to avoid runoff polls in June.

The Dominican Republic's incumbent President Danilo Medina looks poised to win the first round of voting easily in the country's presidential election, early results suggest.

According to preliminary results from 15 percent of polling stations, Medina's coalition won 61 percent of the vote in Sunday's election, a margin that if sustained would be enough to avoid a runoff election in June.

The remaining six candidates combined had less than 4 percent of votes, including the first two women running for the presidency in a Dominican election.

Sunday's election was marred by a shooting at one voting centre, long lines and questions being raised over the vote-counting system after 3,000 poll workers went on strike.

Authorities allowed voting to continue for an extra hour until 23:00 GMT after delays at some centres.

A left-leaning economist, Medina has had high popularity ratings during the latter part of his four-year term in the country of 10.4 million.

Fastest growing economy

Electoral rules were changed to allow him to run for a second consecutive term.

Medina's Dominican Liberation Party has been in power for 12 years.

In the past two years, he has overseen the fastest growing economy in the Americas.

But, despite the strong economy, many Dominicans struggle to meet basic needs, and poverty rates rose to 41 percent in the first year of Medina's term, according to the World Bank.

New schools and health spending in recent years have won Medina support, and poverty has started to decline.

Abinader built his election campaign on a promise to double down on social spending.

He also focused on allegations of corruption related to a power plant awarded to Grupo Odebrecht, a Brazilian engineering conglomerate.

Medina's campaign chief, Joao Santana, returned to Brazil in February to face charges that Odebrecht had paid him funds siphoned from Brazil's state oil company Petrobras in offshore accounts to finance the 2014 election campaign of Dilma Rousseff, the suspended Brazilian president.

Medina has yet to refer to the Petrobras scandal, but he did admit that the Brazilian political strategist was his top adviser. Santana has called the allegations against him "baseless".

Tense relations with Haiti was another important topic in Sunday's general election in Dominican Republic.

Impoverished neighbour

With the fastest growing economy in Latin America in 2014 and 2015, Dominican Republic is considerably wealthier than its poor neighbour Haiti.

The two countries have similar populations but Haitians lag behind on basic facilities including health and education.

Last October's disputed presidential election has left the country without a proper government and many Haitians left their homeland due to a lack of opportunities and political instability.

During his presidency, Medina has overseen the repatriation of tens of thousands of people with roots in Haiti.

Hundreds of thousands of people of Haitian descent have either been deported or lost their Dominican nationality for not having proper documentation.

The policy is popular at home but condemned by human rights groups.

The opposition in the Dominican Republic, on the other hand, claims that the incumbent president's immigration policy is "not strict enough".